Which five statements about hemoglobin and myoglobin structure are true? Each iron atom can form six coordination bonds. Two of these bonds are formed between iron and oxygen. Hemoglobin is a heterotetramer, whereas myoglobin is a monomer. Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron atom. Each hemoglobin or myoglobin molecule can bind four oxygen molecules. Molecular oxygen binds reversibly to Fe2+ in heme. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron atom. Heme is composed of an organic protoporphyrin component and a metal atom.

The following are the true statements:  

1. Heme is not a good oxygen carrier by itself, it must be a component of a larger protein to inhibit oxidation of the iron atom.  

2. Heme comprises an organic protoporphyrin constituent and a metal atom.  

3. Both myoglobin and hemoglobin comprise a prosthetic group known as heme that comprises a central iron atom.  

4. Myoglobin is a monomer, while hemoglobin is a heterotetramer.

5. A molecule of oxygen combines reversibly with the iron (Fe2+) in heme.  

Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs. If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count.

Myoglobin is a protein that's found in your striated muscles, which includes skeletal muscle and heart muscles. Its main function is to supply oxygen to the cells in your muscles . All cells in your body need oxygen in order to function.